The Warren

In 1847, a railway line from West Croydon to Epsom was opened. This was followed in 1868 by another line running from Peckham Rye to Sutton. These two lines now converge just to the east of Sutton town centre railway station and form a triangle of land between the two lines. This area of land is now known as The Warren. The Warren is a Borough Grade II Site of Importance for Nature Conservation (SINC).

The Warren plays an important part in the wildlife corridors of Sutton. It is part of the larger 5.2ha (12.9 acres) East Sutton Railway Lines SINC and provides habitat diversity and continuity within the otherwise suburban sprawl. With a chalk substrate, one can find a typical assortment of calcareous wild flowers in the summer months.

Wildlife & Habitats

This site is managed as chalk grassland, a priority habitat in the UK’s Biodiversity Action Plans. Chalk grasslands develop on shallow, lime-rich soils that are nutrient poor. This enables more specialist species to compete with each other for the low nutrient content, rather than having one or two species dominate. Wildflowers typical of chalk grasslands include marjoram (Origanum vulgare) and field scabius (Knautia arvensis), an infusion of which was traditionally used to treat many ailments. Perforate St. John’s wort (Hypericum perforatum) has been used to treat depression, although recent medical trials don’t particularly support its efficacy. Other plants, such as tufted vetch (Vicia cracca), common knapweed (Centurea nigra) and grass vetchling (Lathyrus nissolia) are all common. Grass vetchling is a particularly difficult plant to find during most of the year, as it’s leaves are almost identical to those of grass. It is only in late spring when the crimson flowers appear that one notices the plant!

Four-spot orb-weaver spider (Araneus quadratus) found at the Warren

The scrub around the edges of the site includes blackthorn (Prunus spinosa), dogwood (Cornus sanguinea), wild privet (Ligustrum vulgare) and a small stand of aspen (Populus tremula). The trees and scrub around the edges of the site are home to several common bird species and even sparrowhawks (Accipter nisus). The variety of ant species within the grasslands provides plenty of food for hungry green woodpeckers (Picus viridus). Common butterfly species that live and feed at The Warren include the gatekeeper (Pyronia tithonus), which looks a bit like a small meadow brown (Maniola jurtina), except that the gatekeeper has to small white dots in the dark upper-wing eyespot, whereas the meadow brown has only one white spot. Common blue (Polyommatus icarus) and marbled white (Melanargia galathea) are good indicator species for chalk grasslands.

Marbled white butterfly

Site Management

Sutton Council and the SNCV have been managing The Warren for nature conservation since 1994. The chalk grassland is kept free from encroaching scrub by annual mowing and scrub clearance. In previous years, the SNCV undertook systematic removal of the non-native species Canadian goldenrod (Solidago Canadensis), which dominated the western part of the meadow. In 2007, there were only a couple of plants occurring, so we have been successful in reducing the impact of this plant on the natural wildflower communities present on site.

A grant from Natural England in 2007 allowed Sutton Council to open the site to the public for the first time, merging the site with Warren Park. Through work with the Downlands Countryside Management Project (DCMP), the SNCV have cleared the scrub belt that separated the wildflower meadow from the amenity grassland of the park.

Originally the chainlink fence and gate were removed, allowing public access to the site. However, as the area runs alongside a public footpath, it was becoming gradually trampled by walkers. As a result a small picket fence was built, restricting access to the nature area but still allowing visitors to observe the site’s plants and animals.